Speaker-related dumb question: speaker SIZE

[slidincharlie (Carlo P)]

Hi there,
I need a replacement speaker for my little old Supro amp, but... I'm not sure if it's a 6" or an 8" speaker!
I'm 'almost' sure that it's an 8 incher.
I had amps with an 8" speaker inside, but I cannot compare sizes by memory.
How should I measure a speaker? Full total diameter including the metal basket? Or rather only the paper cone measured frontally without the metal surrounding?

[Jazz P Bass]

Generally speaking the speaker size is the diameter of the cone, including the surround.

[MWJB]

Basket diameter.

[slidincharlie (Carlo P)]

Thank you guys.